Marine biologist Dr Genefor Walker-Smith said the creatures, which left 16-year-old Sam Kanizay with significant bleeding from his legs, were a small, scavenging crustacean that usually fed on dead fish or sea birds.

Kanizay said on Monday he was soaking his legs at Brighton beach when he felt the creatures attack, causing wounds that would not stop bleeding.

But Walker-Smith told the ABC’s RN Breakfast program the amphipods posed no risk to the public and that it was safe to go back into the water. She said amphipod bites were common and “normally you would feel them or brush them off”.